Fuse adapter



A. SOMMERS FUSE ADAPTER April 12, 1966 Filed July 30, 1962 INVENTOR.

ALEXIS SOMMERS ATTORNEYS United States Patent 3,246,106 FUSE ADAPTER Alexis Sommers, Warren, Pa., assignor to El-Tronics, Inc., Warren, Pa., a corporation of Pennsylvania Filed July 30, 1962, Ser. No. 213,204 4 Claims. (Cl. 200-133) This invention relates to mountings for fuses having mounting terminals of the ferrule type and more particularly to adapters for mounting high-rupture-capacity ferrule fuses in existing fuse holders or mounts.

The National Electrical Manufacturers Association has adopted standards to which fuses of high rupture capacity are now manufactured. These fuses are designated by the industry as either H or J type fuses. The H and J type fuses have an interrupting capacity of 200,000 A.C. amperes at 600 volts and 250 volts, and 100,000 D.C. amperes at 600 volts. The H type ferrule fuse is available in voltage ratings of 600 volts or less and 250 volts or less, and is physically dimensioned to fit into standard clip contacts. The J type ferrule fuse is available in a voltage rating of 600 volts or less, and is physically dimensioned so that it is too short to fit into standard clip contacts. Heretofore, the J type ferrule fuse was useful only in fuse boxes that were specially made to take the J type fuse.

The provision of J type fuses, therefore, tends to obsolete many existing fuse holders or mounts which are designed to accept standard size fuses, such as the H type fuse, but which are in use in applications calling for high rupture capacity of the fuse.

To meet this problem, the present invention provides a device for mounting a high-rupture-capacity ferrule fuse between a pair of fuse clips which the ferrules of the fuse cannot directly engage because the fuse is of the J type and is therefore too short. The device of the present invention mounts a J type ferrule fuse in such a way as to provide clamping engagement between all current-transmitting interfaces so that the adaptation effected by the invention is consistent with proper electrical performance under both operating and fault conditions.

The present invention cables users of I type ferrule fuses to adapt existig ferrule fuse holders or mounts to the special dimensions of J type ferrule fuses, thus avoiding the obsolescence of oversized existing fuse clips or mounts.

By way of example, a description of one specific embodiment of the device is set forth in the accompanying drawings.

In the drawings:

FIGURE 1 is an exploded isometric view of a mounting device, according to this invention, and a J type ferrule fuse.

FIGURE 2 is an isometric view on a reduced scale of the mounting device and J type ferrule fuse of FIGURE 1 in an assembled and mounted condition in a pair of standard fuse clips, and an isometric view of standard size ferrule fuse mounted in an adjacent pair of standard fuse clips for purposes of comparison.

In the illustrated apparatus, a ferrule fuse adapter comprises a a silver plated brass, tubular body 11. The tubular body 11 has a clip-engaging ferrule 12 at one end and an enlarged socket 13 at the other end.

The socket 13 has a cylindrical resiliently dimetrically expandable bore 14 turned into the solid body 11. As may be seen more clearly in FIGURE 1, the socket 13 is divided into a plurality of longitudinally extending, arcuate fingers 15 by slots 16 which are cut into the socket 13. Each of the fingers 15 has a radially inwardly facing arcuate surface defining part of the bore 14. An annular groove 17 is provided on the outside surface of the socket 13, encircling the arcuate fingers 15. Received in the groove 17 is a metal spring circlet 18, preferably spring steel, having an inside diameter which is slightly less than the inside diameter of the groove 17.

A plurality of grooves 19 is provided on the surface of the body 11 for lightning and heat dissipation.

Also illustrated in FIGURE 1 is a I type ferrule fuse 20. The fuse 20 has a tubular body 21 and ferrule end portions 22. The ferrule end portions 22 have an outside diameter which is substantially the same as the diameter of the bore 14.

The ferrule fuse adapter 10 is associated with a J type ferrule fuse by first inserting the circlet 18 over the end of the socket 13 and into the groove 17. Since the inside diameter of the groove 17 and, therefore, the outside diameter of the socket 13 are slightly greater than the inside diameter of the circlet 18, the fingers 15 are bent or flexed inwardly so that as a result of this bending or flexing, the diameter of the bore 14 is slightly less than the outside diameter of the ferrule end portions 22.

A ferrule end portion 22 of the fuse 20 is inserted into the reduced bore 14 by a pushing and twisting motion. This causes the fingers 15 to expand outwardly and to tension the circlet 18 slightly. The pushing and twisting motion, furthermore, insures a tight clamping engagement at the interface defined by the bore 14 and the ferrule end portion 22 inserted therein. This motion also serves to remove any superficial oxidation that may have formed on the ferrule 22 and the bore 14 which would tend to create areas of high resistance at the interface and cause premature failure of the fuse.

When the fuse 20 and the adapter 10 have been assembled in the foregoing manner, the assembly is mounted between a pair of clips 30 and 31 (FIGURE 2). The clips 30 and 31 and the adjacent clips 30a and 31a are standard clip contacts and are spaced to receive standard ferrule fuses such as the fuse 40 which is mounted in the clips 30a and 31a, or the previously described H type ferrule fuse. Even though the fuse 20 is too short to fit into the clips 30 and 311 by itself, the assembly, comprising the fuse 20 and the adapter 10, fits easily into the clips 30 and 31, as is apparent in FIGURE 2.

It should be appreciated that, even though the assembly illustrated in FIGURE 2 includes one fuse adapter 10, any number of adapters may be employed with a fuse. For example, both ferrule end portions 22 of the fuse 20 may be inserted into the sockets of two adapters. Moreover, two or more fuse adapters may be linked together by inserting the clip-engaging ferrule of one into the socket of another. A ferrule fuse may then be inserted into the empty socket in the previously described manner.

The invention is not restricted to the slavish imitation of each and every one of the details described above which have been set forth merely by way of example. Obviously, devices may be provided which change, eliminate, or add certain specific details without departing from the invention.

What is claimed is:

1. A device for mounting a high-rupture-capacity ferrule fuse between a pair of fuse clips which the fuse ferrules cannot engage because the fuse is too short, said device comprising an adapter having a body portion, a clip-engaging ferrule at one end of said body portion, and a fuse-engaging socket at the other end of said body portion, said socket having a bore therein for receiving a fuse ferrule, said b-ore being defined by resiliently radially displaceable arcuate conducting surfaces adapted for association with a ferrule and portion of a fuse to form arcuate conducting interfaces, said arcuate conducting sunfaces defining a bore diameter which is slightly less than the outside diameter of a fuse end portion to be inserted in said bore and Which is slightly less than the outside diameter of said clip engaging ferrule.

2. A device for mounting a high-rupture-capaoity ferrule fuse between a pair of fuse clips which the fuse ferrules cannot engage because the fuse is too short, said device comprising an adapter having a body portion, a clip-engaging ferrule at one end of said body portion, and a fuse-engaging socket at the other end of said body portion, said socket having a bore defined by a plurality of a-rcuate, longitudinally extending, ferrule-gripping fingers, a spring circlet encircling and flexing said fingers to cause said fingers to define a bore diameter which is slightly less than the outside diameter of a fuse ferrule to be inserted in said bore and which is slightly less than the outside diameter of said clip-engaging ferrule.

3. A fuse assembly comprising an adapter having a body portion, a clip-engaging ferrule at one end of said body portion, and a fuse-engaging socket at the other end of said body portion, said socket having a resiliently diametrically expandable bore therein, a fuse having a tubular body and ferrule end portions at either end of said tubular body, one of said ferrule end portions being clampingly engaged by said bore, a first fuse clip engaging the other one of said ferrule end port-ions, and a second fuse clip engaging the ferrule at said one end of said body portion, said bore having a diameter substantially corresponding to the outside diameter of the clipengaging ferrule at said one end of said body portion.

4. A fuse assembly comprising an adapter having a 'body portion, a clip-engaging ferrule at one end of said body portion, and a fuse-engaging socket at the other end of said body portion, said socket having a bore defined by a plurality of arcuate, longitudinally extending, ferrule-gripping fingers, a spring circlet encircling said fingers, a fuse having a tubular body and ferrule end portions at either end of said tubular body, one of said ferrule end portions being received in said bore and clampingly engaged by said fingers, a first fuse clip engaging the other one of said ferrule end portions, and a second fuse clip engaging the ferrule at said one end of said body portion, said bore having a diameter substantially corresponding to the outside diameter of the clip-engaging ferrule at said one end of said body portion.

References Cited by the Examiner UNITED STATES PATENTS 93 8,477 11/ 190-9 Graybill 339-258 1,049,371 1/1913 Kovacs 200-119 1,953,343 4/1934 Frank 200-119 2,363,295 11/1944 Cotter 339-256 2,366,747 1/ 1945 Moody 339-258 2,907,849 10/ 1959 Kobryner 200-119 3,118,035 1/1964 Lebens 200-119 FOREIGN PATENTS 694,140 9/1930 France. 1,020,748 2/1953 France.

BERNARD A. GILHEANY, Primary Examiner. 

3. A FUSE ASSEMBLY COMPRISING AN ADAPTER HAVING A BODY PORTION, A CLIP-ENGAGING FERRULE AT ONE END OF SAID BODY PORTION, AND A FUSE-ENGAGING SOCKET AT THE OTHER END OF SAID BODY PORTION, SAID SOCKET HAVING A RESILIENTLY DIAMETRICALLY EXPANDABLE BORE THEREIN, A FUSE HAVING A TUBULAR BODY AND FERRULE END PORTIONS AT EITHER END OF SAID TUBULAR BODY, ONE OF SAID FERRULE END PORTIONS BEING CLAMPINGLY ENGAGED BY SAID BORE, A FIRST FUSE CLIP ENGAGING THE OTHER ONE OF SAID FERRULE END PORTIONS, AND A SECOND FUSE CLIP ENGAGING THE FERRULE AT SAID ONE END OF SAID BODY PORTION, SAID BORE HAVING A DIAMETER SUBSTANTIALLY CORRESPONDING TO THE OUTSIDE DIAMETER OF THE CLIPENGAGING FERRULE AT SAID ONE END OF SAID BODY PORTION. 